In the heart of the Amazon, where pristine rainforest remains largely untouched by humans, birds are shrinking.
For about four decades, researchers collected and measured 77 species of birds at forest camps. They are not the tie-dye-colored parrots many associate with the Amazon. Instead, they’re mostly nondescript birds that researchers described as “drab” and “brown.”
But in a study published Friday in the journal Science Advances, they’re telling a compelling story — about us, scientists say.
The research suggests that human-caused climate change is piercing even areas considered otherwise largely untouched by people — free of busy roads, pollution and deforestation — and prompting profound changes to the creatures that live there. Every species, on average, weighed less than it had when it was measured in the early 1980s, which the researchers say has no other explanation than a changing environment.
“This study is an example of climate change — human actions globally — affecting a fundamental thing such as the size and shape of these birds in the middle of the Amazon, the symbol of terrestrial biodiversity,” said a lead author on the paper, Vitek Jirinec, a research ecologist.
Birds around the world face climate threats. The U.S. and Canada have lost a quarter of their combined bird populations since 1970, in part because of climate change, a 2019 study found. And unlike many small mammals, which are often nocturnal and able to buffer themselves from temperatures in burrows, nests or caves, birds are constantly exposed to ambient climate conditions, said Blair Wolf, a professor of biology at the University of New Mexico who wasn’t involved in the Amazon research.